Project Summary/Abstract Hematopoietic stem cell transplant (HSCT) is a curative yet rigorous treatment for patients with hematologic malignancies. During the first two years post-HSCT, treatment-related complications such as primary disease relapse, graft-versus-host-disease, and HSCT therapy-related cardio- and musculoskeletal-toxicity contribute to an estimated 60-70% survival rate. Side effects and complications caused by HSCT carry late-effects that negatively impact patients' functional capacity and psychological well-being. As a result, HSCT recipients are at risk of developing co-morbidities such as cardiovascular disease, sarcopenia, and osteoporosis. Due to the increased HSCT symptom burden, HSCT recipients report a 58% decrease in physical activity levels which further perpetuates the loss of skeletal muscle mass, bone density loss, and decreased functional capacity. Exercise has been employed as a successful rehabilitative strategy in HSCT recipients to recuperate losses in skeletal muscle mass, muscular strength and aerobic capacity while concomitantly improving health-related quality of life. While rehabilitative exercises are effective, they do not address the role of preventing physical and mental declines. Prehabilitation, defined as exercise training prior to the start of a medical therapy, has been documented to be valuable in the setting of colorectal and lung cancer patients to positively alter patients' recovery trajectory. Despite the benefits of prehabilitation in other cancer entities, there is a paucity of evidence that investigates the effects of exercise prior to receiving HSCT. The IMPROVE-BMT trial addresses this knowledge gap, with a primary focus on monitoring and reporting objective functional status until 100 days post-transplant. I will take advantage of this planned clinical trial (NCT03886909) to quantify and describe the effects of a combined resistance and aerobic exercise prehabilitation program on skeletal muscle mass, body composition, and bone density for patients receiving a HSCT. To achieve this aim we will conduct a dual- energy x-ray absorptiometry scan at baseline and 100 days post-HSCT. Through this research experience and proposed post-doctoral fellowship, I will learn about the conduct of high quality human clinical trials, clinical exercise prescription for HSCT patients, and will receive training in conduct and interpretation of body composition measurements.